1. Field of the Invention
This invention relates to a one-piece snap hinge closure of plastic, including a lower part and an upper part, or cap, connected with it via a film hinge, which has a security ring or security band injection-molded in one piece to a closure part, as well as at least one recess which is engaged by a respectively protruding bar on the other closure part, so that the two closure parts are locked together in a form-fitting manner prior to removal of the security band.
2. Description of the Prior Art
Plastic closures with security bands have been known for some time. This applies in particular to plastic screw closures for bottles having a screw cap with a security band injection-molded in one piece to it which extends at least approximately completely around the closure. Security bands on snap hinge closures are much less known. This is especially due to the considerably more complicated geometry. Snap hinge closures are for the most part injection-molded in a completely open state and are closed afterwards. In this case it is necessary to bring parts protruding from one closure part into engagement with recesses on the other closure part or on the security band. This requires a high degree of flexibility of the security band, so that the protruding parts which are used as locks and the predetermined breaking points, by which the security band is connected with the closure, are not destroyed during the closing operation.
A snap hinge closure of the above mentioned type with a security band is known from U.S. Pat. No. 4,487,324, for example. To reduce as much as possible the danger of destroying the connection between the security band and the closure, the security band is kept as small as possible and the distance between the individual predetermined breaking points is relatively great. Unfortunately, it has been shown that with relatively little skill it is possible to open this type of snap hinge closure without destroying the security band. One of the reasons for this is that the locking mechanism is clearly visible.
In contrast thereto, U.S. Pat. No. 4,696,408 discloses a snap hinge closure of plastic with a security band extending around half of the circumference of the closure. Here, the security band is injection-molded to the lower part of the closure via appropriate bars and extends far upwards, so that the cap, or the upper closure part, cannot be grasped in the security position of the closure. In a certain embodiment, there is a recess provided in the security band which is engaged by a bar on the upper part of the closure in the security position. However, this only represents an additional lock, the actual securing, however, is associated with arranging the security band around the cap of the closure in such a way that it cannot be grasped in the area opposite the hinge and therefore cannot be opened.
This type of plastic snap hinge closure has proven particularly successful with bottles. However, this type of snap hinge closure with a security band is not suitable for smaller closures, for example for tubes, because the cap is too small for housing an additional user-friendly grasping recess for opening. If the grasping recess is too small, it is necessary to attach a tab for opening. But in this case the tab extends outward to such a degree that it can no longer be covered by the security band, or that in the closing operation it cannot be guided behind the band without destroying the connection of the security band with the lower closure part.